1  declare
  2   function my_sinus (x number) return number is
  3   begin
  4     return sin(x);
  5   end;
  6   function my_cosinus (x number) return number is
  7   begin
  8     return cos(x);
  9   end;
 10   function my_tanges (x number) return varchar2 is
 11   begin
 12     return 'my_tanges('||x||')='||my_sinus(x)/my_cosinus(x);
 13   exception when zero_divide then
 14     return 'Для '||x||' значение неопределено';
 15   end;
 16  begin
 17   dbms_output.put_line(my_tanges(0.8));
 18   dbms_output.put_line(my_tanges(0));
 19   dbms_output.put_line(my_tanges(acos(0)));
 20* end;
SQL> /
my_tanges(,8)=1,02963855705036401274636117282036528417
my_tanges(0)=0
Для 1,5707963267948966192313216916397514421 значение неопределено

PL/SQL procedure successfully completed.